What is the allowable frequency variation as per IE rule of safety?

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ALP CBT 2 Electrician Previous Paper: Held on 22 Jan 2019 Shift 2
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  1. 10%
  2. 3%
  3. 5%
  4. 8%

Answer (Detailed Solution Below)

Option 2 : 3%
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  • As per the Indian Electricity Rules 1956 (amended up to 25th Nov 2000), the permissible range for grid frequency is ± 3 % of nominal i.e. 48.5 Hz to 51.5 Hz.
  • The nominal frequency of operation in the Indian grid is 50.0 Hz and the permissible frequency band specified by Indian Electricity Grid Code (IEGC) is 49.5 Hz to 50.2 Hz with reference to 3rd May 2010.

Some important I.E. rules are given below

IE Rule 50: Supply and use of energy.

IE Rule 54: Declared voltage of supply to the consumer.

IE Rule 55: Declared frequency of supply to the consumer.

IE Rule 30: Service Lines and apparatus on consumer’s premises.

IE Rule 39: Cables protected by bituminous materials.

IE Rule 51: Provisions applicable to medium, high or extra-high voltage installations.

IE Rule 73: Supply to X-ray and high-frequency installation.

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